The crossover (SP1144) and protection circuit are mounted in the base of the cabinet. Connection is made to the drive units (and the front LED) via a single connector. Thus the crossover assembly can easily be completely removed. The components on the top half of the circuit board are the speaker crossover components, whilst those on the bottom half, except the 2x300uF capacitors, are the S-STOP electronic protection. The schematic is shown elsewhere on the site.